The British number one has missed out on automatic qualification for the end-of-season showpiece, which features the best eight players of 2016, but currently occupies the first alternate place.
But her participation in Singapore still hinges on her own fitness and how Carla Suarez Navarro and Svetlana Kuznetsova fare in the Kremlin Cup in Moscow this week.
Konta has enjoyed a stellar year and looked set for automatic qualification after her run to the final of the China Open in Beijing last week.
However, an abdominal injury forced her to pull out of the Hong Kong Tennis Open and will keep her out of Moscow this week, allowing Madison Keys and Dominika Cibulkova to book the final two spots after their results in Linz.
Konta is ninth in the race and in the first alternate spot, the occupant of which gets a place in the tournament if any of the eight qualifiers pull out, something that Williams did on Monday.
The Wimbledon champion has not played since the US Open due to a shoulder injury and withdrew from tournaments in Wuhan and Beijing in order to prepare for the Finals.
However, she has still not recovered and is focusing on her recovery in America.
She said: "I am really, really bombed that I won't be able to compete. It has been a really tough year for me, just dealing with my shoulder injury,
"My doctor insists that I stay home at heal it every single day so I can have a chance to play next year."
That would mean, as things stand and all being well with her fitness, Konta would take Williams' place in the tournament.
However, that situation would change if either Suarez Navarro or Kuznetsova - the top two seeds - win in Moscow this week. The Spaniard is 10th in the race and currently occupying the second alternate spot and Kuznetsova is 11th and either one of those would go above Konta with victory.
If Konta does make it, she will become the first British female since Virginia Wade in 1980 to reach the end-of-season finals.